High energy explosives

ABSTRACT

A high energy explosive composite which comprises 
     (1) from about 2 to about 30 weight percent of an energetic polymer matrixf a urethane which is the reaction product of 
     (a) a hydroxy-terminated prepolymer of the formula ##STR1##  where R is --CH 2  CF(NO 2 ) 2  or --CH 2  C(NO 2 ) 2  CH 3  ; A is --CH 2  CH 2 , --CH 2  OCH 2  --, or --CH 2  OCH 2  OCH 2  --, and n&gt;1, and 
     (b) a polyisocyanate which is used in an amount sufficient to supply from about 0.8:1 to about 1.5:1 isocyanate functional groups for each hydroxy functional group; 
     (2) from about 8 to about 20 weight percent of an energetic plasticizer; and 
     (3) from about 50 to about 90 weight percent of an explosive; 
     wherein the energetic plasticizer and explosives are uniformly dispersed throughout the energetic polymer matrix.

BACKGROUND OF THE INVENTION

This invention relates to explosives and more particularly to highenergy, cast-cured explosives.

At present highly energetic explosives are prepared by melt-castinghighly energetic, but non-melt castable, explosives with less energetic,but melt castable explosives. Unfortunately, these high energy,melt-cast explosives have problems in uniformity of casting, incracking, and in safety characteristics.

Another approach is the cast-curing of high energy, non-melt castableexplosives in binders of energetic plasticizers, inert polymers, andcuratives. However, the inert polymer substantially reduces the energydensity of the resulting explosives.

Thus, it would be desirable to provide cast-curable explosives havinghigher energy densities.

SUMMARY OF THE INVENTION

Accordingly, an object of this invention is to provide a newcast-curable explosive.

Another object of this invention is to provide a cast-curable explosivehaving higher energy.

A further object of this invention is to provide a means forincorporating non-melt castable explosives into high density, highenergy voidless matrices which can be cast-cured.

Yet another object of this invention is to provide high energyexplosives with safe handling characteristics.

These and other objects of this invention are accomplished by providing:

a explosive composite comprising

(1) from about 2 to about 30 weight percent of an energetic polymermatrix of a urethane which is the reaction product of

(a) a hydroxy-terminated prepolymer of the formula ##STR2## where R is--CH₂ CF(NO₂)₂ or --CH₂ C(NO₂)₂ CH₃ ; A is --CH₂ CH₂, --CH₂ OCH₂ --, or--CH₂ OCH₂ OCH₂ --, and n>1, and

(b) a polyisocyanate which is used in an amount sufficient to supplyfrom about 0.8:1 to about 1.5:1 isocyanate functional groups for eachhydroxy functional group;

(2) from about 8 to about 20 weight percent of an energetic plasticizer;and

(3) from about 50 to about 90 weight percent of an explosive;

wherein the energetic plasticizer and explosives are uniformly dispersedthroughout the energetic polymer matrix.

DETAILED DESCRIPTION OF THE INVENTION

First, a mixture of an energetic hydroxy-terminated prepolymer of thegeneral formula ##STR3## where R is --CH₂ CF(NO₂)₂ or --CH₂ C(NO₂)₂ CH₃,A is --CH₂ CH₂ --, --CH₂ OCH₂ --, or --CH₂ OCH₂ OCH₂ --, and n>1 ismixed with an energetic plasticizer and the mixture is dried anddegassed. This can be done by heating the mixture for 1-2 hours undervacuum at 65° C. to 70° C.

Next particles of an energetic explosive such ascyclotetramethylenetetranitramine (HMX) are mixed into theprepolymer/plasticizer until the particles are uniformly dispersedthroughout the mixture. This mixing operation is preferably done at atemperature of from 50° to 80° C., or more preferably 60° to 65° C.

Next the cure catalyst and polyisocyanate curing agent are thoroughlymixed into and dispersed uniformly through theprepolymer/plasticizer/explosive mixture. This step is preferably doneat a temperature of from 50° to 80° C., or preferably 60° to 65° C.

The resulting mixture is cast into suitable devices or molds undervacuum. The molds may be heated or be at room temperature depending onthe flow properties of the mixture and the size or intricacy of themold. The mixture in the mold is then cured with heat at 40° to 60° C.or preferably 48° to 52° C. for about 2 to 7 days.

Prior to curing, the explosive composite mixture comprises: (1) theexplosive, (2) the energetic prepolymer, (3) the energetic plasticizer,(4) the diisocyanate curing agent, and (5) conventional additive such asa cure catalyst, oxidation inhibitors, etc.

The explosive comprises from 50 to 90, preferably from 70 to 85, andmore preferably 78.0 to 81.0 weight percent of the uncured explosivecomposite mixture. The explosive is preferablycyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine(RDX), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB),2,2',4,4',6,6'-hexanitrostilbene (HNS), 3-nitro-1,2,4-triazol-5-one(NTO), nitroguanidine (NQ), or mixtures thereof.

The energetic prepolymer comprises from 1.487 to 21.59, preferably from2.70 to 10.00, and more preferably from 4.09 to 6.71 weight percent ofthe uncured explosive composite mixture.

The energetic prepolymers which may be used to form explosive compositesof the present invention may be represented by the general formula##STR4## where R is --CH₂ C(NO₂)₂ CH₃ or --CH₂ CF(NO₂)₂ and A is --CH₂CH₂ --, or CH₂ OCH₂, or --CH₂ OCH₂ OCH₂ --, and wherein n>1. Theseenergetic polymers are prepared by reacting diols of the formula

    HOCH.sub.2 C(NO.sub.2).sub.2 --A--C(NO.sub.2).sub.2 CH.sub.2 OH

with dichloroformals of the formula ##STR5## where A and R are asdefined above.

Methods of preparing the prepolymers where R is --CH₂ CF(NO₂)₂ aredisclosed in U.S. patent application Ser. No. 06/754,898 filed on May23, 1985, by G. William Lawrence and William H. Gilligan, entitled"Energetic Fluoronitro Prepolymer," (Navy Case No. 68,377), hereinincorporated by reference.

Methods of preparing the prepolymer where R is --CH₂ C(NO₂)₂ CH₃ aredisclosed in U.S. patent application Ser. No. 06/754,897, filed on May23, 1985, by G. William Lawrence and William H. Gilligan entitled"Energetic Nitro Prepolymer," (Navy Case No. 68,397), hereinincorporated by reference.

Specifically, the prepolymers used in this invention are of thefollowing formulas ##STR6## which is prepared by reactingbis(2-fluoro-2,2-dinitroethyl)dichloroformal with2,2,8,8-tetranitro-4,6-dioxanone-1,9-diol; ##STR7## which is prepared byreacting bis(2,2-dinitropropyl)dichlorcformal with2,2,8,8-tetranitro-4,6-dioxanone-1,9-diol; ##STR8## which can beprepared by reacting bis(2-fluoro-2,2-dinitroethyl)dichloroformal with2,2,5,5-tetranitrohexane-1,6-diol; ##STR9## which can be prepared byreacting bis(2,2-dinitropropyl)dichloroformal with2,2,5,5-tetranitrohexane-1,6-diol; ##STR10## which can be prepared byreacting bis(2-fluoro-2,2-dinitroethyl) dichloroformal with2,2,6,6-tetranitro-4-oxaheptane-1,7-diol; and ##STR11## which can beprepared by reacting bis(2,2-dinitropropyl)dichloroformal with2,2,6,6-tetranitro-4-oxaheptane-1,7-diol.

In preparing the polynitroorthocarbonate prepolymers, equimolar amountsof the diol and the dichloroformal can be used, but preferably an excessof the diol is used to assure that the prepolymer product will behydroxy-terminated. The molar ratio of diol to the dichloroformal isfrom 1:1 to 2:1 or preferably from 1.33: 1 to 1.50: 1.

Preferably the average molecular weight of the hydroxyterminatedpolynitroorthocarbonate prepolymer is from 1,000 to 10,000. As the molarratio of diol to dichloroformal is increased, the average molecularweight of the prepolymer produced decreases.

The reaction between a diol and the dichloroformal can be run without asolvent by melting the starting materials. However, it is safer and thuspreferable to use a solvent. Preferred among the solvents are thechlorohydrocarbons such as methylene chloride, 1,2-dichloroethane,1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane,and choloroform, with chloroform being the preferred solvent.Nitromethane also can be used as the solvent.

When bis(2,2-dinitropropyl)dichloroformal is used, the reactiontemperature is preferably from about 40° C. to about 100° C. and morepreferably from 50° C. to 60° C. However, whenbis(2-fluoro-2,2-dinitropropyl)dichloroformal is used, the reactiontemperature is preferably from about 50° C. to about 100° C. and morepreferably from 60° C. to 65° C.

Preferably a rapid stream of dry nitrogen is passed through the reactionmixture to remove hydrogen chloride which is generated by the reactionbetween the diol and dichloroformal. It is advantageous to collect andtitrate the evolved hydrogen chloride to determine and confirm theextent of reaction.

The crude polynitroorthocarbonate material is obtained either by solventevaporation or by decantation of the supernatant liquid from the cooledreaction mixture. Purified material is obtained by extracting the lowmolecular weight impurities from the crude material with suitablesolvents and/or solvent combinations. For example, chloroform or mixtureof a few percent (˜2%) of methanol in chloroform will work.

The starting materials used to prepare the prepolymers may be obtainedas follows:

(1) bis(2-fluoro-2,2-dinitroethyl)dichloroformal can be preparedaccording to the methods disclosed in examples 20 and 21;

(2) bis(2,2-dinitropropyl)dichloroformal can be prepared according tothe method disclosed in example 22;

(3) 2,2,8,8-tetranitro-4,6-dioxanone-1,9-diol, HOCH₂ C(NO₂)₂ CH₂ OCH₂OCH₂ C(NO₂)₂ CH₂ OH, called DINOL, can be prepared by the method taughtat column 4, lines 31-55, of U.S. Pat. No. 3,288,863 titled"Polynitrodiol and Method of Preparation," which issued to Thomas N.Hall and Kathryn G. Shipp on Nov. 29, 1966, herein incorporated byreference;

(4) 2,2,5,5-tetranitrohexane-1,6-diol, HOCH₂ C(NO₂)₂ CH₂ CH₂ C(NO₂)₂ CH₂OH, can be prepared according to the method taught in example 1 atcolumn 2, of U.S. Pat. No. 4,374,241 titled "Nitropolyfomals," whichissued to Horst G. Adolph on Feb. 15, 1983, herein incorporated byreference; and

(5) 2,2,6,6-tetranitro-4-oxaheptane-1,7-diol, HOCH₂ C(NO₂)₂ CH₂ OCH₂C(NO₂)₂ CH₂ OH, can be prepared according to the method taught at column2, line 59 through column 3, line 10 and also at column 3, lines 31-72of U.S. Pat. No. 3,531,534 titled "Bisfluorodinitro Ethers and TheirPreparation," which issued to Horst G. Adolph on Sep. 29, 1970, hereinincorporated by reference.

The energetic plasticizer comprises from 8.0 to 20.0, preferably from11.80 to 15.0, and more preferably from 12.50 to 13.10 weight percent ofthe uncured explosive composite mixture. Preferred energeticplasticizers are bis(2-fluoro-2,2-dinitroethyl)formal (FEFO) , metrioltrinitrate (TMETN), nitroglycerin (NG), 1,2,4-butanetriol trinitrate(BTTN), and 2,2,2-trinitroethyl 2-nitroethyl ether (TNEN) . Alsopreferred are mixtures of (1) bis(2, 2-dinitropropyl)formal(BDNPF) ,bis(2,2,2-trinitroethyl)formal (TEFO), and (2,2,2-trinitroethyl)(2,2-dinitropropyl)formal (TNEPF), and also (2)bis(2,2-dinitropropyl)acetate and bis(2,2-dinitropropyl)formal (A/F).Other suitable energetic plasticizers may also be used.

The hydroxy-terminated polynitroorthocarbonate prepolymers react withconventional polyisocyanates to produce rubbery polyurethane binders.These polyurethane binders have conventional properties such as strengthand flexibility, but they are much more energetic than conventionalpolyurethane binders.

The polyisocyanates comprise from 0.511 to 7.41, preferably from 0.92 to3.43, and more preferably from 1.41 to 2.29 weight percent of theuncured explosive composite mixture. Conventional polyisocyanates whichmay be used include aromatic, aliphatic, and cycloaliphaticpolyisocyanates such as: 2,4-toluene diisocyanate, 2,6-toluenediisocyanate, p-phenylene diisocyanate, 1,5-naphthylene diisocyanate,4,4'-biphenylene diisocyanate, p,p'-methylene diphenyl diisocyanate,1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate,1,10-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate,4,4'-methylene-bis-cyclohexyl isocyanate), 1,5-tetrahydronaphthylenediisocyanate, and polymethylenepolyphenylisocyanate (PAPI), isophoronediisocyanate, and N,N',N"-trisisocyanatohexylbiuret. Mixture ofpolyisocyanates may also be used. Preferred polyisocyanates are2,4-toluene diisocyanate, polymethylpolyphenylisocyanate (PAPI), andN,N',N"-trisisocyanatohexylbiuret. In order to minimize void formation,trifunctional isocyanates such as N,N',N"-trisisocyanatohexylbiuret andthe T-1890's (Huls Chemische Werke) are more preferred. The T-1890's arepolyfunctional oligomers of the cyclic trimer of isophoronediisocyanate. The use of trifunctional alcohols with difunctionalisocyanates will also help to reduce void formation. Suitabletrifunctional alcohols include2-nitro-2-(hydroxymethyl)-1,3-propanediol(Nibglcerol),trimethylolpropane (TMP), as well as trifunctional polycaprolactone[e.g., Union Carbide's PCP 310 (mol wt. 900), PCP 301 (mol. wt. 300),PCP 300 (mol wt. 540)]. The polyisocyanates are used in an amountsufficient to supply from about 0.8:1 to about 1.5:1 but preferably from1:1 to 1.2:1 isocyanate functional groups for each hydroxyl functionalgroup.

The final cured explosive composite comprises the explosive and a binderwhich comprises an energetic polyurethane polymer matrix and theenergetic plasticizer. The weight percent of explosive in the curedcomposite is the same as in the uncured composite: from 50 to 90,preferably from 70 to 85, and more preferably from 78.0 to 81.0 based onthe total weight of the cured explosive composite. Similarly, the weightpercent of energetic plasticizer in the cured explosive composite is thesame as in the uncured composite: from 8.0 to 20.0, preferably from11.80 to 15.0, and more preferably from 12.50 to 13.10 based on thetotal weight of the cured explosive composite. However, the weight ofthe energetic polyurethane polymer matrix in the cured explosivecomposite equals the sum of the weights of the (1) energetic prepolymer,(2) the polyisocyanate, and (3) the additives in the uncured explosivecomposite. Therefore, the weight percent of the energetic polyurethanepolymer matrix is from 2 to 30, preferably 4 to 15, and more preferablyfrom 5.90 to 9.50 weight percent based on the total weight of the curedexplosive composite.

The general nature of the invention having been set forth, the followingexamples are presented as specific illustrations thereof. It will beunderstood that the invention is not limited to these examples but issusceptable to various modifications that will be recognized by one ofordinary skill in the art.

Examples 1 through 18 are summarized in tables 1 (composition ofreaction mixture), 2 (physical properties), and 3 (performance data).

Example 1, 14, and 17 are first presented in detail to illustrate themethod of preparation.

EXAMPLE 1

Bis(2-fluoro-2,2-dinitroethyl)formal (FEFO, 21.086 g), picric acid(1.102 g), and dibutyltin dilaurate (0.149 g) were stirred at 55° C.under vacuum overnight to dry and degas the solution. Prepolymer I(R=--CH₂ CF(NO₂)₂, A=--CH₂ OCH₂ OCH₂ --, 14.80 g, 1033.5 g/equivalenthydroxyl ) was added. After 3 hours at 55° C. under vacuum, thissolution was transferred to a high shear mixer (half pint Baker-Perkin). HMX B (28.125 g), HMX C (42.19 g), HMX C (42.19 g), and aromaticpolyfunctional isocyanate (PAPI, trade name of the Upjohn Co., 0.354 g)and toluenediisocyanate (TDI, 1.052 g) were added sequentially with 15minute mixing cycles under vacuum at 55° C. for each addition. Themixture was vacuum cast into standard JANNAF physical test specimenmolds and heated at 55° C. for 4 days. On removing the specimens thematerial was soft and sticky with a few voids. For composition andphysical properties see example No. 1, Tables 1 and 2, respectively.

EXAMPLE 14

Bis(2-fluoro-2,2-dinitroethyl)formal (FEFO 384.74 g) and prepolymer II(R=--CH₂ C(NO₂)₂ CH₃, A=--CH₂ OCH₂ OCH₂ --, 174.29 g, 1479 g/equivalenthydroxyl) were stirred in a high shear mixer (one gallon Baker-Perkin)at 65°-70° C. for 2 hours under vacuum to degas and dry the solution.HMX B (600 g), HMX C (900 g), HMX C (900 g), and 2-nitrodiphenylamine(2NDPA, 6.072 g), and poly functional oligomers of cyclic trimers ofisophoronediisocyanate (T-1890s, Huls Chemische Werke, 40.0 g) anddibutyltin sulfide (T-5, M & T Chemicals, 0.03 g) were addedsequentially with 15 minute mixing cycles under vacuum at 60°-65° C. foreach addition. The mixture was vacuum cast into tubes and heated at48°-52° C. for 12 days. On x-raying the samples, no voids, cracks, orbubbles were found. See Example No. 14, Tables 1, 2, and 3 forcomposition, physical properties, and performance data respectively.

EXAMPLE 17

bis(2-fluoro-2,2-dinitroethyl)formal (FEFO, 16.86 g), metriol trinitrate(TMETN, 2.95 g), and prepolymer II (R=--CH₂ C(NO₂)₂ CH₃, A=--CH₂ OCH₂OCH₂ --, 8.83 g, 885 g/equivalent hydroxyl) were stirred in a high shearmixer (half pint Baker-Perkin) at 65°-70° C. for 1.5 hours under vacuum.HMX B (38.0 g), HMX C (59.85 g), HMX C (59.85 g), andN-methyl-4-nitroaniline (MNA, 0.287 g) and 2-nitrodiphenyl amine (2NDPA,0.287 g), and polyfunctional oligomers of cyclic trimers ofisophoronediisocyanate (T-1890s, Huls Chemische Werke, 3.56 g) andmaleic anhydride (MA, 0.574), and triphenylbismuth (Ph₃ Bi, 0.043 g)were added sequentially with 15 minute mixing cycles under vacuum at60°-65° C. for each addition. The mixture was vacuum cast into standardJANNAF tensile specimens and cured at 48°-52° C. for 7 days. On removingthe specimens from the molds the material was found to be fairly strong,not sticky, with no obvious voids. For composition and physical propertydata see Example No. 17, tables 1 & 2, respectively.

The following glossary defines the abbreviations used in Table 1.

NOMENCLATURE Plasticizers

FEFO=Bis(2-fluoro-2,2-dinitroethyl)formal

TMETN=Metriol trinitrate

Additives

PA=Picric acid

TMP=Trimethylolpropane

EG=Ethyleneglycol

DEG=Diethyleneglycol

PCP310+Trifunctional polycaprolactone (mol. wk.=900)

PCP301=Trifunctional polycaprolactone (mol. wt.=300)

PCP300=Trifunctional polycaprolactone (mol. wt.=540)

(Note: PCP300, PCP301, and PCP310 are available from Union Carbide)

TP=N-Phenyltoluenesulfonamide

2NDPA=2-Nitrodiphenylamine

MNA=N-Methyl-p-nitroaniline

DHE=Bis(hydroxyethyl)hydantoin

NC=Nitrocellulose (11.87% N, 254 eq. wt.)

Isocyanates

TDI=Toluenediisocyanate

PAPI=Aromatic polyfunctional isocyanate (Upjohn Co.)

IPDI=Isophorone diisocyanate

T-1890s--Polyfunctional oligomers of the cyclic trimer of IPDI

Catalysts

T-12=Dibutyltin dilaurate

T-5--Dibutyltin sulfide

ZnOct.=Zinc Octoate

Ph₃ Bi=Triphenylbismuth

FEAA=Ferric acetylacetonate

MA=Maleic anhydride

Example 19 illustrates the preferred explosive composite (embodiment).It was prepared according to the methods taught in this specification.

                                      TABLE 1                                     __________________________________________________________________________    EXPLOSIVE COMPOSITION BY WEIGHT PERCENT                                       EXAMPLE                                                                              PREPOLYMER.sup.(1)                                                                      PLASTICIZER.sup.(2)                                          No.    (EW)      (FEFO)   ADDITIVES                                                                              ISOCYANATES                                                                            CATALYST HMX                                                                                HMX                 __________________________________________________________________________                                                              B                   1      9.78      13.45    0.733    0.705/0.256                                                                            0.098    56.25                                                                              18.75                      (1034)             (PA)     (TDI/PAPI)                                                                             (T-12)                            2      7.44      13.06    0.258    1.056    0.018    58.62                                                                              19.54                      (1290)             (TMP)    (TDI)    (T-12)                            3      6.84      11.97    0.159/0.0538                                                                           0.962    0.0118   60.00                                                                              20.00                      (1329)             (TMP/EG) (TDI)    (ZnOct.)                          4      5.969     12.93    0.102/0.119                                                                            0.840    0.0197/0.204                                                                           69.997                                                                             9.998                      (1329)             (TMP/DEG)                                                                              (TDI)    (ZnOct./Ph.sub.3 Bi)              5      5.998     13.00    0.046/0.111                                                                            0.750    0.0281/0.090                                                                           55.99                                                                              23.99                      (1892)             (TMP/DEG)                                                                              (IPDI)   (FEAA/T-5)                        6      5.958     12.91    0.067/0.159                                                                            0.835    0.0118   60.20                                                                              19.86                      (1329)             (TMP/DEG)                                                                              (TDI)    (T-5)                             7      5.956     12.91    0.0668/0.159                                                                           0.835    0.019/0.019                                                                            60.18                                                                              19.85                      (1329)             (TMP/DEG)                                                                              (TDI)    (ZnOct/Ph.sub.3 Bi)               8      5.93      12.86    0.0744/0.197                                                                           0.832    0.0198/0.0396                                                                          60.27                                                                              19.78                      (1329)             (PCP301/DEG)                                                                           (TDI)    (ZnOct./Ph.sub.3 Bi)              9      6.04      12.89    0.043/0.152/0.051                                                                      0.719    0.099/0.639                                                                            60.03                                                                              20.01                      (1584)             (TMP/DEG/TP)                                                                           (TDI)    (ZnOct./Ph.sub.3 Bi)              10     5.99      13.11    --       0.720/1.422                                                                            0.0532   60.00                                                                              20.00                      (1892)                      (IPDI/T-1890s)                                                                         (T-5)                             11     5.68      12.54    0.195    0.000/1.58                                                                             0.0093   60.00                                                                              20.00                      (1253)             (2NDPA)  (IPDI/T-1890s)                                                                         (T-5)                             12     5.66      12.76    0.202    0.000/1.38                                                                             0.00275  60.00                                                                              20.00                      (1476)             (2NDPA)  (IPDI/T-1890s)                                                                         (T-5)                             13     5.82      12.74    0.200    0.163/0.933                                                                            0.00150  60.00                                                                              20.00                      (1476)             (2NDPA)  (IPDI/T-1890s)                                                                         (T-5)                             14     5.68      12.54    0.194    0.00/1.58                                                                              0.0093   60.00                                                                              20.00                      (1476)             (2NDPA)  (IPDI/T-1890s)                                                                         (T-5)                             15     5.98      13.20    0.200    0.598    0.0040   60.00                                                                              20.00                      (1365)             (CaSO.sub.4)                                                                           (PAPI 94)                                                                              (T-5)                             16     5.36      12.15    0.177/0.377                                                                            0.254/1.68                                                                             0.0178   60.00                                                                              20.00                      (1500)             (2NDPA/DHE)                                                                            (IPDI/T-1890s)                                                                         (T-5)                             17     4.525     9.31/1.04                                                                              0.234/0.0301                                                                           0.00/1.827                                                                             0.0757/0.0302                                                                          62.95                                                                              19.98                      (885)     (FEFO/TMETN)                                                                           (MNA/NC) (IPDI/T-1890s)                                                                         (MA/Ph.sub.3 Bi)                  18     4.526     8.69/1.55                                                                              0.151/0.151                                                                            0.00/1.874                                                                             0.0302/0.0226                                                                          63.00                                                                              20.00                      (885)     (FEFO/TMETN)                                                                           (MNA/2NDPA)                                                                            (IPDI/T-1890s)                                                                         (MA/Ph.sub.3 Bi)                  __________________________________________________________________________     .sup.(1) Prepolymer I (R = --CH.sub.2 CF(NO.sub.2).sub.2, A =  --CH.sub.2     OCH.sub.2 OCH.sub.2) was used in example 1. Prepolymer II (R = --CH.sub.2     C(NO.sub.2).sub.2 CH.sub.3, A = CH.sub.2 OCH.sub.2 OCH.sub.2) was used in     the remaining examples 2 through 18. The hydroxyl equivalent weights (EW)     are given in parenthesis beneath the weight percentages.                      .sup.(2) Plasticizer used in examples 1 through 16 was                        bis(2fluoro-2,2-dinitroethyl)formal (FEFO). in examples 17 and 18 a           mixture of FEFO and metriol trinitrate (TMETN) was used as the                plasticizer.                                                             

                                      TABLE 2                                     __________________________________________________________________________    PHYSICAL PROPERTIES OF CAST EXPLOSIVES                                           Viscosity                                                                            Pot Life                                                                              Density                                                                            S.sub.m.sup.(1)                                                                  E.sub.m.sup.(2)                                                                     W.sup.(4)                                                                         Shore A                                   No.                                                                              (EOM, KP)                                                                            (HRS to 20 KP)                                                                        (g/mL)                                                                             (psi)                                                                            (%)                                                                              Y.sup.(3)                                                                        (ft-lb)                                                                           Hardness                                  __________________________________________________________________________    1  --     --      1.795                                                                              13.0                                                                             41.3                                                                              52                                                                              0.372                                                                             11                                        2  13.3   0.67    1.748                                                                              83.0                                                                             7.26                                                                             1520                                                                             0.304                                                                             77                                        3  25     0       1.773                                                                              102.0                                                                            10.15                                                                            1379                                                                             0.519                                                                             78                                        4  25     0       1.770                                                                              86.                                                                              7.74                                                                             1512                                                                             0.321                                                                             72                                        5  30     0            NO Cure                                                6  19.8   --      1.750                                                                              66 6.78                                                                             1215                                                                             0.223                                                                             74                                        7  19.2   --      1.710                                                                              48 8.79                                                                              800                                                                             0.228                                                                             66                                        8  12.0   --      1.480                                                                              26 9.46                                                                              359                                                                             0.131                                                                             40                                        9  9.4    1.5     1.580                                                                              25 10.86                                                                             352                                                                             0.158                                                                             31                                        10 32     0       1.748                                                                              Poor Casting 50                                        11 6      --      1.813                                                                              47 4.63                                                                             1268                                                                              0.0412                                                                           70                                        12 8      2.5     1.822                                                                              62 4.63                                                                             1681                                                                              0.0608                                                                           75                                        13 18.8   --      1.814                                                                              43 5.56                                                                              583                                                                              0.0675                                                                           62                                        14 7.3    3.5     1.812                                                                              -- -- -- --  35                                        15 11.9   --      1.815                                                                              43 10.2                                                                              569                                                                             0.123                                                                             50                                        16 15.1   --           93 6.48                                                                             1690                                                                             0.100                                                                             85                                        17 24.3   0            67 7.87                                                                             1252                                             18 13.28                                                                      __________________________________________________________________________     .sup.(1) S.sub.m = Maximum stress                                             .sup.(2) E.sub.m = Elongation at maximum stress                               .sup.(3) Y = Modulus                                                          .sup.(4) W = Area under stressstrain curve                               

                                      TABLE 3                                     __________________________________________________________________________    PERFORMANCE DATA FOR CAST EXPLOSIVES                                             Vacuum Thermal                                                                         Impact Sen.                                                                          Large Scale                                                                          Detonation                                             Stability                                                                              50% Height                                                                           Gap Test                                                                             Velocity                                                                            Growth   Exudation                            No.                                                                              (48 hrs, cc/g)                                                                         (cm)   (cards)                                                                              (mm/sec)                                                                            (% vol. Change)                                                                        (%)                                  __________________________________________________________________________    2  0.83     31.7   --     --    --       --                                   9  --       --     --     --    -2.02    0                                    11 0.92     --     --     --    --       --                                   12 0.94     --     --     --    --       --                                   14 --       --     177    8.545 -0.46    0.28                                 15 1.15     --     --     0     --       --                                   __________________________________________________________________________

EXAMPLE 19

    ______________________________________                                                                       Percent By                                     Component.sup.1 Function       Weight                                         ______________________________________                                        HMX Grade B, Class 3                                                                          High Explosive 60.00                                          HMX Grade B, Class 2                                                                          High Explosive 20.00                                          Gilligan Prepolymer No. II                                                                    Energetic prepolymer                                                                         4.88                                           Bis(2,2,2-fluorodinitro-                                                                      Energetic plasticizer                                                                        13.042                                         ethel formal (FEFO)                                                           IPDI-T1890s     Crosslinking Agent                                                                           1.675                                          (polyisocyanate of                                                            isophorone diisocyanate)                                                      2-nitrodiphenylamine                                                                          Stabilizer     0.164                                          N-Methyl-4-nitroaniline                                                                       Stabilizer     0.164                                          Maleic anhydride                                                                              Cure agent     0.049                                          Triphenylbismuth                                                                              Cure catalyst  0.025                                          ______________________________________                                         .sup.1 Gilligan prepolymer II (R = --CH.sub.2 C(NO.sub.2).sub.2 CH.sub.3,     A = --CH.sub.2 OCH.sub.2 OCH.sub.2 --, 1479 g/equivalent hydroxyl) see        formula (II) on page 7.                                                  

Examples 20 and 21 illustrate methods by which thebis(2-fluoro-2,2-dinitroethyl)dichloroformal starting material can beprepared. These examples are taken from U.S. patent application Ser. No.06/256,462 which was filed on Mar. 30, 1981, by William H. Gilligan andwhich now is under a D-10 order.

EXAMPLE 20 Bis(2-fluoro- 2,2-dinitroethyl)dichloroformal (Prior Art)

To a solution of 10.0 g (28.6 mmol) of bis(2-fluoro-2,2-dinitroethyl)thionocarbonate in 50 ml of freshly distilled sulfuryl chloride wasadded 4.0 ml of titanium tetrachloride. The solution was then refluxedfor 5 days. Excess sulfuryl chloride and titanium tetrachloride werethen removed in vacuo at a bath temperature of 50° C. The solid residuewas recrystallized from chloroform to give 7.91 g (71%) ofbis(2-fluoro-2,2-dinitroethyl)dichloroformal as colorless crystals, mp57°-58° C.

H - NMR (CDCl₃ /TMS) δ (ppm) - d, 5.02.

Calc. for C₅ H₄ Cl₂ F₂ N₄ O₁₀ : C, 15.44; H, 1.04; Cl, 18.23; F, 9.77;N, 14.40 Found: C, 15.46; H, 1.05; C1, 18.40; F, 9.98; N, 14.11.

EXAMPLE 21 Bis(2- fluoro-2,2-dinitroethyl)dichloroformal (Prior Art)

Gaseous chlorine was slowly passed into a stirred slurry of 21.0 g(0.067 mol) of bis(2-fluoro-2,2-dinitroethyl)thionocarbonate in 100 mlof dry carbon tetrachloride and 10 ml of dry trifluoroethanol for 4.5hours at the end of this period the slurry had changed into a clearorange-colored solution. After standing overnight, volatiles wereremoved on a Rotovac and the solid residue was recrystallized fromchloroform to give 19.33 g (83%) ofbis(2-fluoro-2,2-dinitroethyl)dichloroformal, m.p. 57°-8° C.

The bis(2-fluoro-2,2-dinitroethyl)thiocarbonate used in examples 20 and21 can be prepared according to the method disclosed in example 1 ofU.S. Pat. No. 4,172,088, entitled"Bis(2-Fluoro-2,2-dinitroethyl)thionocarbonate and a method ofPreparation," which issued on Oct. 23, 1979, to Angres et al.

Example 22 illustrates a method by which thebis(2,2-dinitropropyl)dichloroformal starting material can be prepared.This example is taken from U.S. patent application Ser. No. 06/256,462which was filed on Mar. 30, 1981, by William H. Gilligan and which nowis under a D-10 order.

EXAMPLE 22 Bis(2,2-dinitropropyl)dichloroformal (Prior Art)

Gaseous chlorine was passed into a solution of 3.1 g (9.1 mmol) ofbis(2,2-dinitropropyl)thionocarbonate in 7 ml ofacetonitrile/1,2-dichloroethane mixture (3/4; v/v) for 51/2 hours. Afterstanding overnight, the solvents were removed and the solid residuerecrystallized from 1,2-dichloroethane to give 3.2 g (93%) of product,m.p. 121°-3° C.

H - NMR (acetone-Cl₆ /TMS) δ (ppm) - s, 5.04; s, 2.39

Calc for C₇ H₁₀ N₄ O₁₀ Cl₂. C, 22.06; H, 2.65; C1, 18.61. Found: C,22.30; H, 2.68; Cl, 18.28.

The bis(2,2-dinitropropyl)thiocarbonate used in Example 22 is preparedaccording to a method disclosed in Example 1 of U.S. Pat. No.4,323,518,entitled "Polynitroethylthiocarbonates and Method of Preparation", whichissued on Apr. 6, 1982, to William H. Gilligan, herein incorporated byreference.

Examples 23 and 24 illustrate the preparation of the prepolymers usingbis(2-fluoro-2,2-dinitroethyl)dichloroformal and2,2,8,8-tetranitro-4,6-dioxanone-1,9-diol as the starting materials.These examples are incorporated from U.S. patent application Ser. No.06/754,898, filed on May 23, 1985, supra.

EXAMPLE 23 prior art

To a three-necked, round bottomed flask equipped with a nitrogen inlet,a motor driven stirrer, and an insulated spiral condenser outlet whichwas cooled at -30° C. were added2,2,8,8-tetranitro-4,6-dioxanonane-1,9-diol (DINOL, 20.0 g, 0. 0581 mol), bis(2-fluoro-2,2-dinitroethyl)dichloroformal (19.31 g, 0.0496 mol)and 1,2-dichloroethane (13.0 mL). A preheated 75° C. oil bath was raisedaround the flask causing the contents to form a solution quickly. Arapid, steady stream of nitrogen was passed through the solution via asintered glass sparge tube throughout the course of the reaction. Aftersix days, 98.24% of the calculated amount of hydrogen chloride had beentrapped by an aqueous sodium hydroxide solution (0.1N). A white solidwas isolated by evaporation of the solvent under vacuum and allowing thefoam thus formed to solidify. The hydroxyl equivalent weight correctedfor the extent of reaction was 1785, measured from the decrease in theinfrared absorption of toluenesulfonylisocyanate. The number averagemolecular weight calculated from the reactant ratio corrected for theextent of reaction was 3792. Thus, the functionality was 2.12.

EXAMPLE 24

2,2,8,8-tetranitro-4,6-dioxanonane-1,9-diol (60.0 g, 0.174 mol),bis(2-fluoro-2,2-dinitroethyl)dichloroformal (54.25 g, 0.139 mol), andethanol-free chloroform (51.0 mL) were added to a three-necked, roundbottomed flask equipped with a nitrogen sparge tube inlet, an insulated,spiral condenser outlet at -25° C., and a motor driven stirrer. Apreheated 60°-65° C. oil bath was raised around the flask causing thecontents to form a solution quickly. A rapid, steady stream of nitrogenwas passed through the solution throughout the course of the reaction.After 25 hours, 81% of the calculated amount of hydrogen chloride hadbeen trapped in an aqueous sodium hydroxide (0.1N) solution. Thesupernatant liquid was decanted from the cooled mixture. The residue inthe flask was extracted with stirring two times with 2%methanol-chloroform and two times with 100% chloroform. The remainingsolvent was removed in vacuo, and the solid foam was powdered.

Yield: 69.85 g (66.93% overall yield, 95.92% based on the extent ofreaction). The hydroxyl equivalent weight of the material, corrected forthe presence of some (˜5-8%) nonfunctional cyclic orthocarbonate, was998.3 g/eq. OH. Analysis by gel permeation chromatography gave thefollowing corrected values: weight average molecular weight of 2830,number average molecular weight of 2121, and dispersity of 1.33. Thus,the average functionality of the chains above 1000 molecular weight is2.12.

Examples 25 and 26 illustrate the preparation of the prepolymers usingbis(2,2-dinitropropyl)dichloroformal and2,2,8,8-tetranitro-4,6-dioxanane-1,9-diol as starting materials. Theseexamples are incorporated from U.S. patent application Ser. No.06/754,897 filed on May 23, 1985, supra.

EXAMPLE 25 (prior art)

To a flask equipped with a nitrogen inlet, a motor-driven stirrer and aninsulated spiral condenser at -30° C. was added 76 ml of ethanol-freechloroform. After placing the flask in a 55° C. oil bath, 41.15 g (0.108mol) of bis(2,2-dinitropropyl)dichloroformal and 43.36 g (0.126 mol) of2,2,8,8-tetranitro-4,6-dioxanonane-1,9-diol were added. A steady streamof nitrogen was passed through the solution during the course of thereaction. After 5 hours at 55° C., 100.3% of the theoretical amount ofhydrogen chloride had been collected. The reaction mixture was thencooled and the upper layer of chloroform was removed by decantation. Thebottom layer containing the polymer was washed four times with 70 ml ofchloroform by heating to 55° C. for several hours with efficientstirring, then cooling the mixture and removing the chloroform bydecantation. After washing, the residual solvent was removed in vacuo togive, after grinding a white powder. Analysis by gel permeationchromatography gave the following values: weight average molecularweight, 4477; number average molecular weight, 2896; dispersity, 1.55and functionality, 1.99.

EXAMPLE 26 (prior art)

b 2,2,8,8-tetranitro-4,6-dioxanonane-1,9-diol (103.2 g, 0.30 mol) wasdissolved in 190 ml ethanol-free chloroform at 55° C. in a resin flaskequipped with a nitrogen inlet, a motor-driven stirrer and an insulatedspiral condenser at -35°. Then 91.50 g (0.24 mol) ofbis(2,2-dinitropropyl)dichloroformal was added and the stirred reactionmixture was held at 55° C. for 7 hours while a steady stream of nitrogenwas passed through the mixture. The reaction mixture was cooled and theupper layer of chloroform was removed by decantation. The lower layercontaining the polymer was extracted four times with 100 ml ofchloroform (vide supra). The residual solvent was removed in vacuo andthe solid polymer was powdered. Analysis gave the following values:weight average molecular weight, 3870; number average molecular weight,2621; dispersity, 1.48 and functionality, 1.96.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

We claim:
 1. An explosive composite comprising:(1) from about 2 to about 30 weight percent of an energetic polymer matrix of a urethane which is the reaction product of(a) a hydroxy-terminated prepolymer of the formula ##STR12## where R is selected from the group consisting of --CH₂ CF(NO₂)₂ and --CH₂ C(NO₂)₂ CH₃ --, and A is selected from the group consisting of --CH₂ CH₂, --CH₂ OCH₂ --, and --CH₂ OCH₂ OCH₂ --, and n>1, and (b) a polyisocyanate which is used in an amount sufficient to supply from about 0.8:1 to about 1.5:1 isocyanate functional groups for each hydroxy functional group; (2) from about 8 to about 20 weight percent of an energetic plasticizer; and (3) from about 50 to about 90 weight percent of an explosive; wherein the energetic plasticizer and explosive are uniformly dispersed throughout the energetic polymer matrix.
 2. The explosive composite of claim 1 wherein R is --CH₂ CF(NO₂)₂.
 3. The explosive composite of claim 1 wherein R is --CH₂ C (NO₂)₂ CH₃.
 4. The explosive composite of claim 1 wherein A is --CH₂ CH₂ --.
 5. The explosive composite of claim 1 wherein A is --CH₂ OCH₂ --.
 6. The explosive composite of claim 1 wherein A is --CH₂ OCH₂ OCH₂ --.
 7. The explosive composite of claim 1 comprising (a) from 4 to 15 weight percent of energetic polymer matrix, (b) from 11.8 to 15.0 weight percent of energetic plasticizer, and (c) from 70 to 85 weight percent of explosive.
 8. The explosive composite of claim 7 comprising (a) from 5.90 to 9.50 weight percent of energetic polymer matrix, (b) from 12.50 to 13.10 weight percent of energetic plasticizer, (c) and from 78.0 to 81.0 weight percent of explosive.
 9. The explosive composite of claim 1 wherein the energetic plasticizer is selected from the group consisting of bis(2-fluoro-2,2-dinitroethyl)formal, metriol trinitrate, nitroglycerin, 1,2,4-butanetriol trinitrate, 2,2,2-trinitroethyl 2-nitroethyl ether, and a binary mixture of bis(2,2-dinitropropyl)formal and bis(2,2-dinitropropyl)acetate.
 10. The explosive composite of claim 9 wherein the energetic plasticizer is bis(2-fluoro-2,2-dinitroethyl)formal.
 11. The explosive composite of claim 1 wherein the explosive is selected from the group consisting of cyclotetramethylenetetranitramine, cyclotrimethylenetrinitramine, 1,3,5-triamino-2,4,6-trinitrobenzene, 2,2',4,4',6,6'-hexanitrostilbene, 3-nitro-1,2,4-triazol-5-one, nitroguanidine, and mixtures thereof. 